How To Bash Shell Find Out If a Variable Is Empty Or Not

To find out if a variable is empty or not in Bash shell, you can use the -z operator.

The -z operator allows you to test if a variable is empty or not. If the variable is empty, the -z operator returns true; otherwise, it returns false.

Here is an example of how you can use the -z operator to test if a variable is empty or not:

# Define the variable
var=""

# Test if the variable is empty
if [ -z "$var" ]; then
  echo "The variable is empty"
else
  echo "The variable is not empty"
fi

This will output "The variable is empty", because the variable var is empty.

You can also use the -z operator to test if a variable is set or not. If the variable is set, even if it is empty, the -z operator will return false.

For example:

# Define the variable
var=""

# Test if the variable is set
if [ -z "${var+x}" ]; then
  echo "The variable is not set"
else
  echo "The variable is set"
fi

This will output "The variable is set", because the variable var is set, even though it is empty.

Overall, the -z operator is a useful tool for testing if a variable is empty or not in Bash shell. It allows you to easily determine if a variable is empty or not, and perform tasks based on the value of the variable.